In a gas turbine for power generation which is configured by a compressor, a combustor, a turbine, etc., the temperature of air taken into the compressor affects output of the turbine. For instance, in summer season when the atmospheric temperature is high, density of the intake air decreases and thus a mass flow rate decreases, hence the output of the turbine decreases. To suppress this sort of decrease in output of the turbine, intake air cooling systems have been developed, including an intake air cooling system equipped with an intake air cooling coil for lowering the temperature of air taken in from outside by heat exchange with cooling medium and an intake air cooling system which sprays water to the intake air to cool the intake air using heat of vaporization of the sprayed water. With the intake air cooling system equipped with the intake air cooling coil, moisture in the atmosphere is cooled by heat exchange with the intake air cooling coil and condensed into drain water. The drain water is then collected by a drain pan arranged below the intake air cooling coil and is discharged from a drain pipe.
In the case where this intake air cooling system is used, however, the drain water adhering to a surface of the intake air cooling coil may scatter to a downstream side along with the intake air passing through the intake air cooling coil, or the drain water may fail to be collected by the drain pan and leak from the drain pan. Therefore, there are issues such as damage to blades of the compressor caused by erosion or lock of the compressor due to entry of the drain water into the compressor disposed on the intake side of the gas turbine. As a conventional technique for preventing the drain water from entering the compressor of the gas turbine, Patent Reference 1 discloses an intake air cooling device for a gas turbine, in which a mist removing means is provided on a downstream side of the intake duct of a vaporizer so as to remove mist from the intake air by collecting unvaporized mist. Further, Patent Reference 2 discloses a gas turbine which is provided with grooves that are formed in rotation symmetry in an inner wall surface of a flow passage, where operating air supplied with water flows, or in a rotor or a casing flow passage surface of the gas turbine, so as to collect mist adhering to the inner wall surface or the flow passage surface.